Protecting the Stratospheric Ozone Layer

Did you know?

Ozone-destroying chemicals
escape into the air and reach the
stratosphere. Over time they reduce
the layer of stratospheric ozone that
protects us.

When the protective ozone layer is damaged, there is an increase in
harmful rays from the sun reaching the Earth. These rays can harm
both health and the environment.

Service stations must have special equipment that prevents
release of refrigerant chemicals to the air when they
are recharging car air conditioning systems.

Ozone can be good or bad depending on where
it is located. Close to the Earth's surface, ground-level
ozone is a harmful air pollutant. Ozone in the
stratosphere, high above the Earth, protects human
health and the environment from the sun's harmful
ultraviolet radiation. This natural shield has been
gradually depleted by manmade chemicals. So in
1990, Congress added provisions to the Clean Air Act
for protecting the stratospheric ozone layer.

Ozone in the stratosphere, a layer of the atmosphere
located 10 to 30 miles above the Earth, serves as a
shield, protecting people and the environment from the
sun's harmful ultraviolet radiation. The stratospheric
ozone layer filters out harmful sun rays, including a type
of sunlight called ultraviolet B. Exposure to ultraviolet
B (UVB) has been linked to cataracts (eye damage) and
skin cancer. Scientists have also linked increased UVB
exposures to crop injury and damage to ocean plant life.

In the mid-1970s, scientists became concerned that
chlorofluorocarbons (CFCs) could destroy stratospheric
ozone. At that time, CFCs were widely used as aerosol
propellants in consumer products such as hairsprays
and deodorants, and as coolants in refrigerators and
air conditioners. In 1978, the U.S. government banned
CFCs as propellants in most aerosol uses.

Scientists have been monitoring the stratospheric
ozone layer since the 1970s. In the 1980s, scientists
began accumulating evidence that the ozone layer
was being depleted. The ozone hole in the region of
the South Pole, which has appeared each year during
the Antarctic winter (our summer), often is bigger
than the continental United States. Between 1978 and
1997, scientists have measured a 5 percent loss of
stratospheric ozone-a significant amount.

Over 190 countries, including the major industrialized
nations such as the United States, have signed the
1987 Montreal Protocol, which calls for elimination of
chemicals that destroy stratospheric ozone. Countries
that signed the Protocol are committed to limiting the
production and use of those chemicals.

The 1990 Clean Air Act required EPA to set up a
program for phasing out production and use of ozone-destroying
chemicals. In 1996, U.S. production
ended for many of the chemicals capable of doing the
most serious harm such as CFCs, halons, and methyl
chloroform.

Unfortunately, it will be about 60 years before the
stratospheric ozone layer heals. Because of the ozone-destroying
chemicals already in the stratosphere
and those that will arrive within the next few years,
stratospheric ozone destruction will likely continue
throughout the decade. September 24, 2006, tied for
the largest ozone hole on record at 29 million square
kilometers (11.4 million square miles). The year 2006
also saw the second largest sustained ozone hole.

The Clean Air Act includes other steps to protect the
ozone layer. The Act encourages the development
of "ozone-friendly" substitutes for ozone-destroying
chemicals. Many products and processes have been
reformulated to be more "ozone-friendly." For
instance, refrigerators no longer use CFCs.

Sometimes it isn't easy to phase out an ozone-destroying
chemical. For instance, substitutes have
not been found for CFCs used in certain medical
applications. The limit on the production of methyl
bromide, a pesticide, was extended because farmers
did not yet have an effective alternative. Despite the
inevitable delays because of technical and economic
concerns, ozone-destroying chemicals are being
phased out, and, with continued work, over time the
protective ozone layer will be repaired.